Pipe cutter

ABSTRACT

A pipe cutter for cutting a pipe includes a cutting head assembly having a first carriage and a second carriage spaced apart to define a cutting area. The first carriage supports a cutting mechanism, and the second carriage is configured to support a pipe within the cutting area. The carriages have a locked state and an unlocked state such that when the carriages are in the unlocked state, the carriages are movable relative to each other and biased into the cutting area. The pipe cutter also includes a drive assembly configured to rotate the cutting head assembly and a locking mechanism configured for changing the carriages from the unlocked state to the locked state and for holding the carriages in the locked state. The locking mechanism includes an actuation member rotatably coupled to the first carriage.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application claims priority to U.S. ProvisionalPatent Application Ser. No. 60/895,062, titled “PIPE CUTTER” filed onMar. 15, 2007, and also claims priority to U.S. Provisional PatentApplication Ser. No. 60/990,862, titled “PIPE CUTTER” filed on Nov. 28,2007, the entire contents of both are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a cordless power tool andmore specifically, to a battery-powered pipe cutter.

Power-operated pipe cutters perform cutting operations in a variety ofmanners, many of which are largely automated. However, these methods ofcutting oftentimes require manual intervention at some point during thecutting process, including, for example, loading a pipe within the pipecutter, adjusting the pipe cutter to accommodate different pipe sizes,and applying a cutting force to the pipe. Such manual intervention canbe time consuming and result in imperfect cuts.

SUMMARY OF THE INVENTION

In one embodiment, the invention provides a pipe cutter for cutting apipe. The pipe cutter includes a cutting head assembly having a firstcarriage and a second carriage spaced apart to define a cutting area.The first carriage supports a cutting mechanism, and the second carriageis configured to support a pipe within the cutting area. The carriageshave a locked state and an unlocked state such that when the carriagesare in the unlocked state, the carriages are movable relative to eachother and biased into the cutting area. The pipe cutter also includes adrive assembly configured to rotate the cutting head assembly and alocking mechanism configured for changing the carriages from theunlocked state to the locked state and for holding the carriages in thelocked state. The locking mechanism includes an actuation memberrotatably coupled to the first carriage. Rotation of the cutting headassembly causes rotation of the actuation member relative to the firstcarriage. The locking mechanism also includes a locking memberconfigured for engagement with the first carriage and the secondcarriage upon rotation of the actuation member. Engagement of thelocking member with the first carriage and the second carriage holds thecarriages in the locked state.

In another embodiment, the invention provides a pipe cutter for cuttinga pipe including a cutting head assembly having a first carriage and asecond carriage spaced apart to define a cutting area. The firstcarriage includes a cutting mechanism and a biasing arm having a firstportion and a second portion, wherein the first portion of the biasingarm supports the cutting mechanism. The second carriage is configured tosupport a pipe within the cutting area. The carriages have an unlockedstate and a locked state for cutting the pipe. The pipe cutter alsoincludes a drive assembly configured to rotate the cutting head assemblyand an actuation member rotatably coupled to the second portion of thebiasing arm. Upon rotation of the cutting head assembly, the actuationmember rotates relative to the first carriage and deflects the biasingmember toward the second carriage such that the first carriage is in thelocked state and a force acts on the cutting mechanism to cut the pipe.

In yet another embodiment, the invention provides a pipe cutter forcutting a pipe. The pipe cutter includes a cutting head assembly havinga first carriage that includes a cutting mechanism and a biasing arm. Asecond carriage is spaced apart from the first carriage to define acutting area, and includes a support surface for supporting a pipewithin the cutting area. The cutting head assembly also includes anover-center position for the pipe which is defined by the cuttingmechanism and the support surface. The carriages have an unlocked statefor inserting the pipe into the cutting area and a locked state forcutting the pipe such that when the first carriage is in the unlockedstate the first carriage is movable relative to the second carriage andis biased into the cutting area. The cutting head assembly also includesa spring biasing the second carriage into the cutting area such thatwhen the second carriage is in the unlocked state, the second carriageis movable relative to the first carriage. The pipe cutter also includesa drive assembly configured to rotate the cutting head assembly and alocking mechanism configured for moving the carriages from the unlockedstate to the locked state and for holding the carriages in the lockedstate when the pipe is positioned in the over-center position. Thelocking mechanism includes an actuation member rotatably coupled to thefirst carriage such that rotation of the cutting head assembly causesrotation of the actuation member relative to the first carriage, and alocking member configured for engagement with the first carriage and thesecond carriage upon rotation of the actuation member. Engagement of thelocking member with the first carriage and the second carriage holds thecarriages in the locked state.

In still another embodiment, the invention provides a pipe cutter forcutting a pipe. The pipe cutter includes a housing having a cutting headportion and a handle portion, wherein a cutting head assembly iscontained within the cutting head portion of the housing. The cuttinghead assembly includes a first carriage and a second carriage spacedapart to define a cutting area. The first carriage supports a cuttingmechanism and includes a biasing arm having a first portion supportingthe cutting mechanism and a second portion. The second carriage includesa support surface. The cutting mechanism and the support surface definean over-center position for the pipe. The carriages have an unlockedstate and a locked state such that when the carriages are in theunlocked state, the carriages are movable relative to each other andbiased into the cutting area. The pipe cutter also includes a springbiasing the second carriage into the cutting area and a drive assemblyconfigured to rotate the cutting head assembly. The cutting headassembly further includes a cam member rotatably coupled to the secondportion of the biasing arm such that rotation of the cutting headassembly causes rotation of the cam member relative to the firstcarriage, and a locking member configured for engagement with the firstcarriage and the second carriage upon rotation of the cam member.Engagement of the locking member with the carriages holds the carriagesin the locked state. The cutting head assembly also includes an actuatormember fixed relative to the cutting head assembly. The actuator memberengages the cam member as the cutting head assembly rotates to rotatethe cam member.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pipe cutter according to oneembodiment of the invention.

FIG. 2A is a side view of the pipe cutter shown in FIG. 1 with housingportions of the pipe cutter removed to illustrate internal gearmechanisms.

FIG. 2B is a perspective view of a handle portion of the pipe cuttershown in FIG. 1 with a battery pack disengaged from the pipe cutter.

FIG. 3 is a perspective view of the pipe cutter shown in FIG. 1 withhousing portions of the pipe cutter removed to illustrate a cutting headassembly.

FIG. 4 is an enlarged view of the cutting head assembly shown in FIG. 3.

FIGS. 5A-5D illustrate various positions of the cutting head assemblyshown in FIG. 4 during a cutting operation.

FIG. 6 is a bottom view of a portion of the cutting head assembly shownin FIG. 4.

FIGS. 7A-7C illustrate the cutting head assembly shown in FIG. 4 duringinsertion of the pipe.

FIG. 8 is a perspective view of the upper and lower carriages shown inFIGS. 6-7C with portions of the upper carriage, including a spring,removed to illustrate an upper carriage body.

FIGS. 9A-9B are perspective views of the upper and lower carriages shownin FIGS. 6-8 with portions of the upper carriage body removed.

FIG. 10 is a front perspective view of the upper and lower carriagesshown in FIGS. 6-9 with portions of the upper carriage removed toillustrate a cutting wheel.

FIG. 11 is a side perspective view of the upper and lower carriagesshown in FIG. 10.

FIG. 12 is a top view of the pipe cutter shown in FIG. 1.

FIG. 13 is side view of a cutting head portion of another embodiment ofa pipe cutter with housing portions of the pipe cutter removed toillustrate a cutting head assembly.

FIG. 14 is a perspective view of a pipe cutter according to yet anotherembodiment of the invention.

FIG. 15 is a side view of the pipe cutter shown in FIG. 14 with housingportions of the pipe cutter removed to illustrate a drive assembly.

FIG. 16 is a side view of a forward portion of the pipe cutter shown inFIG. 14 with housing portions removed to illustrate a cutting headassembly.

FIG. 17 is a perspective view of the cutting head assembly shown in FIG.16.

FIG. 18 is another side view of the cutting head assembly shown in FIG.14 with housing portions removed to illustrate a timing gear andportions of the cutting head assembly.

FIG. 19 is a side view of cutting head assembly of the pipe cutter shownin FIG. 16-17.

FIG. 20 is cross-section side view of the cutting head assembly shown inFIG. 19.

FIG. 21 is a top view of a portion of the pipe cutter shown in FIG. 16with housing portions removed to illustrate a portion of the cuttinghead assembly

Before at least one embodiment of the invention is explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of the construction and the arrangements ofthe components set forth in the following description or illustrated inthe drawings. The invention is capable of other embodiments and of beingpracticed or carried out in various ways. In addition, it is understoodthat the phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting.

DETAILED DESCRIPTION

FIGS. 1-12 show a pipe cutter 100 according to one embodiment of theinvention. The pipe cutter 100 is a hand-held, battery-operated pipecutter, although according to another embodiment, the pipe cutter 100may be a corded pipe cutter. The pipe cutter 100 is configured to cut avariety of pipe sizes and materials. In the illustrated embodiment, thepipe cutter is configured to cut metal pipes having ⅜ inch through 1inch nominal inner diameter (i.e., ½ inch to 1⅛ inch outer diameter).Such metal pipes may include any type of copper having thicknesses K, L,and M, electric metallic tubing (conduit) of ¾ inch and 1 inch,aluminum, brass, and other metal pipes.

The pipe cutter 100 includes a housing 105 having a forward portion 110and a handle portion 115. The housing 105 forms an exterior of the pipecutter 100 and contains various mechanical and/or electrical componentsof the pipe cutter 100. The housing 105 may be a hard plastic material,a metal material, and/or any other material or combination of materialssuitable for containing the various components of the pipe cutter 100.The forward portion 110 includes components configured for conducting acutting function of the pipe cutter 100 and includes an opening 106 forreceiving a pipe. The handle portion 115 is configured to be gripped bya user with one or two hands. The handle portion 115 also houses,supports, or is coupled to a variety of mechanical or electricalcomponents of the pipe cutter 100.

In the illustrated embodiment, the handle portion 115 includes a batterypack 120, a switch assembly 125, and a motor 130. The pipe cutter 100 isoperable to receive power from the battery pack 120. According toanother embodiment, the pipe cutter 100 may be powered by an alternatingcurrent (AC) power provided via a corded plug electrically coupled to awall outlet or any number of suitable powering options.

As shown in FIGS. 1-3, the battery pack 120 is removably coupled to thehandle portion 115 to provide power to the pipe cutter 100. In theillustrated embodiment, the battery pack 120 is supported within abattery chamber 135 extending through a rearward end of the handleportion 115 of the housing 105. The battery pack 120 includesreceptacles (not shown) configured to connect to battery terminals 133located within the battery chamber 135. When the battery pack 120 isdisengaged from the battery chamber 135, as shown in FIG. 2B, thebattery terminals 133 are exposed. The battery pack 120 generallyconforms to the contour of the handle portion 115 such that, when thebattery pack 120 is inserted into the battery chamber, the battery pack120 helps define and increase the size of the handle portion 115. Wheninserted or coupled, the battery pack 120 provides power to the motor130 through a control circuit 131 or may power the motor 130 directly.The control circuit 131 controls various aspects of the pipe cutter 100,the motor 130 and/or the battery pack 120 and may also monitor operationof the pipe cutter 100 and its components.

The battery pack 120 includes two actuators 132 to releasably secure thebattery pack 120 in the chamber 135. Each actuator 132 is connected to atab 134 that engages a corresponding recess 129 in the chamber 135 (FIG.2B). Due to the resiliency of the material of the housing 105, the tabs134 are biased away from the battery casing to engage the recesses.Depressing the actuators 132 moves the tabs 134 out of engagement withthe corresponding recesses such that the battery pack 120 may bedisconnected from the pipe cutter 100. This arrangement allows a user toquickly remove the battery pack 120 from the device 100 for rechargingor replacement.

In the illustrated embodiment, the battery pack 120 is a twelve-volt(12V) rechargeable power tool battery pack. The illustrated battery pack120 may include three (3) battery cells having, for example, a lithium(Li), lithium-ion (Li-ion), or other lithium-based chemistry. Forexample, the battery cells may have a chemistry of lithium-cobalt(Li—Co), lithium-manganese (Li—Mn) spinel, or Li—Mn nickel. In suchembodiments, each battery cell may have a nominal voltage of about, forexample, 3.6V, 4.0V, or 4.2V. In other embodiments, the battery cellsmay have a nickel-cadmium, nickel-metal hydride, or lead acid batterychemistry. In further embodiments, the battery pack 120 may includefewer or more battery cells, and/or the battery cells may have adifferent nominal voltage. In yet another embodiment, the battery pack120 may be a dedicated battery housed (partially or entirely) within thepipe cutter 100. The battery pack 120 may also be configured for usewith other cordless power tools, such as drills, screwdrivers, grinders,wrenches, and saws.

The pipe cutter 100 shown in the illustrated embodiment also includes aswitch assembly 125, which is operable to electrically connect the motor130 to the battery pack 120. The switch assembly 125 includes a push,power switch 126 and a pivoting, direction switch 127 positioned on thehandle portion 115 of the housing 105. When actuated by a user, thepower switch 126 activates the power supply 120 of the pipe cutter 100.The direction switch 127 is movable between three positions: a forwardposition and a reverse position for controlling the rotational directionof the motor 130 and a cutting head assembly 145, and a lock-outposition for preventing inadvertent powering of the motor 130.

The handle portion 115 and the switch assembly 125 may be gripped by auser in a number of ways. Referring to FIG. 1, the handle portion 115includes a dual position grip configured to accommodate two differentone-handed grip styles, a lower grip position and an upper gripposition. In a lower grip position, a user grasps a lower hand grip 136such that the switch assembly 125 is located between the user's hand andthe forward portion 110 of the pipe cutter 100. The user actuates theswitch assembly 125 with an index finger of the same hand that isgripping the handle portion 115. In an upper grip position, the usergrasps an upper hand grip 137 such that the user's hand is positionedbetween the switch assembly 125 and the forward portion 110 of the pipecutter 100. The user actuates the switch assembly 125 with a ring fingeror pinky finger of the same hand that is gripping the handle portion115. The option of using the lower grip position and the upper gripposition allows a user to adjust a grip to best suit individual handsize and strength and to accommodate for confined workspaces or pipeconfigurations. It should be readily apparent to those of skill in theart that a user may utilize a two-handed grip style with the handleportion 115 of the pipe cutter 100.

Referring to FIGS. 2A and 3, a drive assembly 140 is supported by theforward portion 110 of the housing 105. The drive assembly 140 ispowered by the motor 130 and drives the cutting head assembly 145 to cuta pipe (not shown). In the illustrated embodiment, the motor 130 isdrivingly coupled to gears (not shown) housed within a gear case 149.The gears are drivingly coupled to a bevel gear set, including a bevelgear 153 and a bevel pinion 154, which drives the drive assembly 140. Ina further embodiment, the motor 130 is coupled to a gear reduction, suchas a planetary gear reduction, with a pinion which couples to and drivesa drive gear 150. In yet another embodiment, the motor 130 is coupleddirectly to the drive assembly 140.

The drive assembly 140 also includes a clutch, such as a clutch 151(FIG. 3). The clutch cam 151 is driven by the bevel gear 153 and isslidably coupled to a drive axle 152 of the drive gear 150. The clutch151 functions when the pipe cutter 100 is operated in a reversedirection and is configured to slip out of engagement with the bevelgear 153 when the amount of torque placed on the drive assembly 140exceeds a certain threshold. This threshold is reached during reverseoperation of the cutting head assembly 145 as the cutting head assemblyis returned to its original “home” position and meets resistance tofurther rotation, as discussed below with respect to FIG. 5A. Meetingthis resistance, the clutch 151 slips out of engagement with the bevelgear 153 and slides along the drive axle 152. Disengagement of theclutch 151 and the bevel gear 153 terminates rotation of the drive axle152 and thus, terminates rotation of the entire drive assembly 140 andthe cutting head assembly 145. In another embodiment, the drive assembly140 includes a single two-direction clutch that operates in both forwardand reverse directions.

As shown in FIG. 2A, the drive assembly 140 includes the drive gear 150,a first idler gear 155, a second idler gear 160, and a C-shaped headgear 165. The drive gear 150, the first idler gear 155, and the secondidler gear 160 are mounted to a stationary frame 172, which is supportedby the housing 105. The head gear 165 is coupled to the cutting headassembly 145 such that an opening 173 in the head gear 165 is alignedwith an opening 171 in the cutting head assembly 145. In the illustratedembodiment, the first and second idler gears 155, 160 are spaced apart adistance such that at least one of the first and second idler gears 155,160 is in contact with the head gear 165 at all times, even when theopening 173 of the head gear 165 rotates past the idler gears 155, 160.

The handle portion 115 of the housing 105 and the forward portion 110 ofthe housing 105 are separated by a seal 174 (FIG. 2A) that serves towaterproof the pipe cutter 100 for use in wet conditions. The seal 174may take a variety of forms, such as an O-ring or other type of seal. Inthe illustrated embodiment, the seal 174 is an O-ring that preventsliquid from entering the pipe cutter 100 at any point rear of the driveassembly 140. The O-ring 174 is located in a circumferential grooveformed in the gear casing 149. So that the pipe cutter 100 may be safelyused in potentially wet conditions, the pipe cutter 100 componentsforward of the seal 174 may be formed of materials appropriate for usein water and resistant to excessive wear and tear under such conditions.In the illustrated embodiment, all components contained within theforward portion 110 of the housing 105 are formed of stainless steel or,in the case of a cutting wheel 170, aluminum.

As shown in FIGS. 3-4, the cutting head assembly 145 is located in theforward portion 110 of the housing 105. FIGS. 5A-5D illustrate thecutting head assembly 145 with the housing 105 and the remainder of thepipe cutter 100 removed, and the cutting head assembly 145 in a varietyof positions during a cutting operation. In the illustrated embodiment,the cutting head assembly 145 includes a cutting head housing 146, whichcontains an upper carriage 175 and a lower carriage 180. A space betweenthe upper carriage 175 and the lower carriage 180 forms a cutting area185 into which pipes of various sizes are inserted. In the illustratedembodiment, the upper carriage 175 and lower carriage 180 are configuredto move independently of each other so that a pipe is inserted withouthaving to preconfigure the size of the cutting area 185 for the pipe'sdiameter. The upper and lower carriages 175, 180 may be formed from avariety of materials including metal and plastic. Although the upper andlower carriages 175, 180 are configured to move independently, thecarriages 175, 180 are coupled by one or more parts, couplers,fasteners, pivot points, etc. As shown in FIG. 6, the upper and lowercarriages 175, 180 are slidably coupled together at a stem 295 of thelower carriage 180. Although the carriages 175, 180 are described asupper and lower carriages, it should be understood that they may belocated relative to each other in a different manner. For example, thecarriage described as the upper carriage 175 may be located in theposition of the lower carriage 180 and vice versa.

In the illustrated embodiment, the upper carriage 175 includes thecutting wheel 170, such as a blade. The cutting wheel 170 is a sharpblade suitable for cutting pipe of various materials, including metal.The cutting wheel may be formed of various types of metal depending onthe type of pipe to be cut, and may include abrasive particles. Theillustrated cutting wheel 170 is circular, although the cutting tool maybe formed in varying other shapes, such as an oval shape, a polygon,etc. The cutting wheel 170 may have a smooth and sharp edge, may have anuneven or asymmetrical edge with teeth or protrusions, or otherwise. Inthe illustrated embodiment, the cutting wheel 170 is formed of aluminumand has a circular shape with a smooth edge. The cutting wheel 170includes a central aperture 190 (FIGS. 10-11). The central aperture 190may be circular or have another shape. The cutting wheel 170 may bepermanently fixed within the pipe cutter 100 or may be replaceable. Theupper carriage 175 further includes an axle 195 that is coupled to thecutting wheel 170 at the aperture 190 and around which the cutting wheel170 rotates.

Referring to FIGS. 7A-7C and 8-11, the upper carriage 175 includes abody 200 configured to support the cutting wheel 170. The body 200 ofthe upper carriage 175 includes an upper body portion 205 and a lowerbody portion 210. The upper portion 205 of the upper carriage body 200includes a space 215 separating a first upper body portion 216 and asecond upper body portion 217 (FIG. 8). In the illustrated embodiment,the cutting wheel 170 is positioned within the space 215. The first andsecond upper body portions 216, 217 of the upper carriage body 200 eachinclude an opening, such as a slot 220 (FIG. 8), in which the cuttingwheel axle 195 rides. The slots 220 may be formed in a variety of shapesof sufficient size to support the axle 195. In the illustratedembodiment, the slots 220 are formed such that the cutting wheel axle195 has sufficient room to move up and down within the slots 220, andthereby move toward and away from the lower carriage 180.

The upper carriage 175 includes one or more biasing mechanisms, such assprings 225, 226 shown in the illustrated embodiment. Each of thesprings 225, 226 includes a first portion 230 and a second portion 235,whereby the first portions 230 include one or more apertures (not shown)aligned with the slots 220 of the upper carriage body 220 and throughwhich the cutting wheel axle 195 is mounted. The cutting wheel 170 rideson the axle 195, which rests within the slots 220 of the upper carriagebody 200 and the apertures of the first portions 230 of the first andsecond springs 225, 226.

Each of the first and second springs 225, 226 includes an aperture 245in the second portion 235. The apertures 245 are configured to receiveand interact with a mechanical element of the upper or lower carriages175, 180, such as a cam 250. In the illustrated embodiment, the uppercarriage 175 includes a rotatable cam 250 having a cam shaft 255, a camlever 260, and a cam post 265. As shown in FIGS. 9A and 9B, each of thesecond portions 235 of the springs 225, 226 includes the aperture 245for receiving the cam shaft 255. The cam shaft 255 extends through thefirst spring 225, the second portion 210 of the upper carriage body 200(FIG. 8), and the second spring 226. In the illustrated embodiment, thecam shaft 255 is a dual cam shaft that serves two functions, anautomatic spring-loading function and an automatic locking function, asdiscussed below. The cam lever 260 extends from one end of the cam shaft255 and terminates at the cam post 265. The cam shaft 255 has agenerally cylindrical shape, and referring to FIG. 9A, includes firstcam surfaces 270 and a second cam surface 275. The first cam surfaces270 act on the springs 225, 226 to perform an automatic spring-loadingfunction, and the second cam surface 275 acts on a lifter element 360 toperform an automatic locking function, as discussed below.

The lower carriage 180 is generally configured to provide a forceagainst the pipe during pipe loading and pipe cutting activities.Referring to FIGS. 7A-7C, the lower carriage 180 is biased toward theupper carriage 175 and into the cutting area 185 by a spring 280, suchas a light spring. It should be readily apparent to those of skill inthe art that in a further embodiment the lower carriage 180 may be actedupon by any type of biasing element.

As shown in FIGS. 7A-7C, the lower carriage 180 includes a body 282supporting rollers 285, 286, which define a support surface for a pipe.It should be noted that although two rollers are shown in theillustrated embodiment, one or more rollers or no rollers may beprovided within the lower carriage 180 for defining a support surface.For example, the lower carriage 180 may include one or more surfaces,bumpers, or other structures configured to support and/or press againsta pipe when a pipe is inserted into the cutting area 185.

The first and second rollers 285, 286 may be formed of a variety ofmaterials, such as metal or plastic. In the illustrated embodiment, thefirst and second rollers 285, 286 are formed of stainless steel. Therollers may also be formed in a variety of shapes, although in theillustrated embodiment, the rollers 285, 286 are formed in generallycylindrical shapes. In the illustrated embodiment, circumferentialgrooves 290 (FIG. 10) are formed in the rollers to support a pipe with aflare fitting and allow a user to remove a flared end of a pipe whileminimizing the length of pipe to be removed. The grooves 290 are locatedin an off-center position of each roller 285, 286 relative to thecutting wheel 170. The off-center location of the grooves 290 allows theflared end of a pipe to rest within the grooves 290 while the length ofpipe is firmly supported by the first and second rollers 285, 286 duringthe cutting operation.

Referring to FIGS. 6, 8 and 9A, the upper carriage 175 receives a stem295, or a support member, of the lower carriage 180 to slidably couplethe upper and lower carriages 175, 180 together. The stem 295 extendsfrom the lower carriage body 282, toward the upper carriage 175, andadjacent to a rear of the cutting area 185. The stem 295 may beintegrally formed with the body 282 of the lower carriage 180 or may bea separate component coupled to the lower carriage body 282. The stem295 includes one or more notches 300 spaced such that each notchcorresponds to a pipe diameter, as discussed below.

As shown in FIGS. 7A-7C, the upper and lower carriages 175, 180 allowpipes having a variety of sizes to be quickly loaded into the pipecutter 100 such that a pipe 302 is automatically aligned and supportedwithin the cutting head assembly 145 prior to initiation of a cuttingoperation. To this end, the upper and lower carriages 175, 180 arebiased toward each other and shaped so as to guide a pipe into thecutting area 185. The lower carriage 180 includes a forward portionhaving a forward angled surface 320 that extends toward the cutting area185 and terminates along a centerline of the first roller 285. Each ofthe first and second springs 225, 226 include a forward angled surface305 that extend to form a protrusion 310 on the lower surfaces of thesprings 225, 226. The protrusions 310 are located opposite the firstroller 285. Moving inward from the protrusions 310, each lower surfaceof the springs 225, 226 defines a second angled surface 315 extendingaway from the lower carriage 180 and to the rear of the cutting area185.

As shown in FIG. 7A, the forward angled surface 305 of the first andsecond springs 225, 226 and the forward angled surface 320 of the lowercarriage 180 cooperate to guide a pipe 302 into the cutting area 185. Assuch, the forward angled surfaces 305, 320 may be symmetrical. Theprotrusions 310 of the cutting springs 225, 226 cooperate with the firstroller 285 (FIG. 7B) such that when the pipe 302 is forced past theprotrusions 310 and the first roller 285, the pipe 302 reaches anover-center position (FIG. 7C). In the over-center position, the pipe302 is centered between the first and second rollers 285, 286 of thelower carriage 180 and is aligned with the cutting wheel 170 of theupper carriage 175.

The upper and lower carriages 175, 180 include surfaces 325, 330 toprevent the pipe 302 from moving too far into the cutting area 185 suchthat it would no longer be supported between the first and secondrollers 285, 286 and the cutting wheel 170, i.e., in the over-centerposition. As shown in FIGS. 7A-7C, a rear upper portion of the lowercarriage 180 includes an angled surface 325 extending toward the uppercarriage 175 and to the rear of the cutting area 185. Likewise, aportion of the upper carriage 175 located to the rear of the cuttingarea 185 includes an angled surface 330 extending toward the lowercarriage 180 and to the rear of the cutting area 185.

In preparation for use of the pipe cutter 100, a user selects a pipe 302to be cut and positions the pipe 302 within the cutting area 185. Priorto pipe insertion, the upper and lower carriages 175, 180 areindependently and freely movable in an unlocked state. As the pipe 302enters the cutting area 185, the pipe 302 presses against the forwardangled surfaces 305, 320 of the upper and lower carriages 175, 180, asshown in FIG. 7A. The force of the pipe insertion overcomes the biasesof the spring 280 on the lower carriage 180 and the springs 225, 226 onthe upper carriage 175, thereby forcing the upper and lower carriages175, 180 away from each other, as shown in FIG. 7B. The force of thepipe's insertion on the first and second springs 225, 226 also moves thecutting wheel axle 195 and cutting wheel 170, away from the lowercarriage 180. The movement of the upper and lower carriages 175, 180away from each other accommodates the specific diameter of the pipe 302and allows the pipe 302 to move further into the cutting area 185. Asthe pipe 302 continues to move into the cutting area 185, the pipe 302passes the protrusions 310 on the upper carriage 175 and the firstroller 285 of the lower carriage 180 in a centered position. As the pipe302 moves past the protrusions 310 and the first roller 285, the pipe302 reaches an over-center position, as shown in FIG. 7C. When the pipe302 reaches this over-center position, the upper and lower carriages175, 180 snap onto the pipe 302 such that the pipe 302 is firmlysupported between the rollers 285, 286 and the cutting wheel 170.

When inserting the pipe into the pipe cutter 100 as described above, theuser may view the cutting area 185 through a sight window 335 (FIG. 12).In the illustrated embodiment, the pipe cutter 100 includes a sightwindow 335 located in a wall 340 of the housing 105 proximate thecutting head assembly 145. The sight window 335 allows a user to viewthe cutting area 185 of the pipe cutter 100 through the wall 340 of thehousing 105. The cutting head assembly 145 includes an aperture 342(FIGS. 5A-5D) aligned with the sight window 335 to continue the line ofsight. The sight window 335 allows a user to properly align a pipe withthe cutting wheel 170 and to observe the cutting process during use ofthe pipe cutter 100. The sight window 335 may be formed of a variety ofmaterials, including Plexiglas, as shown in the illustrated embodiment,or other transparent materials suitable for use in a power tool.Alternatively, the sight window 335 may include an opening with nocovering.

Referring to FIG. 4, the pipe cutter 100 includes a light source 345,such as an LED, to illuminate the cutting area 185. The light source 345is located within the forward portion 110 of the housing 105 andadjacent to the sight window 335. The light source 345 is activated viaa light switch (not shown). The light switch may be electrically coupledwith or separate from the switch assembly 125 of the pipe cutter 100.The light switch may be configured to remain activated at all timesduring the operation of the pipe cutter 100 or only for a certain periodof time, such as for 5 or 10 minutes. Alternatively, the light switchmay be configured to be activated any time contact with a pipe isinitiated by the cutting head assembly 145.

Once the pipe is located in the over-center position within the pipecutter 100, the user may initiate the cutting process by activating thepower supply 120 of the pipe cutter 100. To activate the power supply120, the user moves the direction switch 127 into a forward position andengages the power switch 126. Activation of the power supply 120 of thepipe cutter 100 causes the motor 130 to drive the drive assembly 140and, in turn, rotate the cutting head assembly 145.

Referring to FIG. 5A, the cutting head assembly 145 starts in anoriginal home position in which the opening 173 of the head gear 165 isaligned with the opening 171 of the cutting head assembly 145 and theopening 106 of the housing 105. As the drive assembly 140 initiallyrotates the cutting head assembly 145 in a forward direction about anaxis 351, the cam post 265 of the rotatable cam 250, engages an elementfixed within the housing 105, such as a fixed cam or cam actuator 355coupled to an interior of the forward portion 110 of the housing 105.Upon engagement of the cam post 265 with the cam actuator 355, the cam250 rotates about an axis 352 such that the cam post 265 is forcedtoward an outer periphery 350 of the cutting head housing 146, as shownin FIG. 5B. The cam 250 continues to rotate about the axis 352 until thecam lever 260 is aligned with the outer periphery 350 of the cuttinghead housing 146, as shown in FIG. 5C, such that the cam 250 may movepast the cam actuator 355.

Rotation of the cam 250 facilitates loading of the springs 225, 226 ofthe cutting head assembly 145. As shown in FIGS. 9A-9B, rotation of thecam 250 applies a load to the first and second springs 225, 226 bypulling the springs into the cutting area 185 and toward the lowercarriage 180. As the cam 250 rotates, the first cam surfaces 270 pullthe first and second springs 225, 226 toward the lower carriage 180.Loading of the springs 225, 226 applies a force to the cutting wheelaxle 195, and consequently, to the cutting wheel 170 and the uppercarriage body 200. Application of the load causes the cutting wheel axle195 to translate within the slots 220 of the upper carriage body 200 andpresses the cutting wheel 170 firmly against the pipe with forcesufficient to cut the pipe.

Rotation of the cam 250 also locks the upper and lower carriages 175,180 relative to each other in a position appropriate for the diameter ofthe inserted pipe. Prior to loading a pipe into the cutting area 185,the upper and lower carriages 175, 180 are in an unlocked state and areindependently movable relative to each other (FIGS. 7A-7C, 9A, and 10).When the cam 250 rotates as described above with respect to FIGS. 5A-5C,the second cam surface 275 of the cam shaft 255 raises a lifter element360 located within a lower portion 361 of the upper carriage 175 (FIGS.9B and 11). The cam 250 raises the lifter element 360 into contact witha locking plate 365. The lifter element 360 includes a first portionthat engages the cam shaft 255 and a second portion that engages thelocking plate 365. As shown in FIGS. 10-11, the locking plate 365 issubstantially planar and includes an upper surface 366, a lower surface367, a forward portion 368, and a rearward portion 369. An aperture 371extends through the upper and lower surfaces 366, 367 and is configuredfor receiving the stem 395.

When the carriages 175, 180 are in the unlocked state (FIGS. 9A, 10),the locking plate 365 is freely movable along a longitudinal axis of thestem 295. As the cam shaft 255 rotates, the lifter element 360 movesrelative to the stem 295 and pushes against the rearward portion 369 ofthe locking plate 365 thereby pivoting the locking plate 365 about thestern 295 and the forward portion 368 toward the lower carriage 180. Thepivoting action moves the upper surface 366 of the locking plate 365into engagement with one of the stem notches 300 (FIGS. 9B, 11). Each ofthe notches 300 corresponds to a different pipe size. In the illustratedembodiment, the notches 300 are configured for ASTM B88 standard pipesizes. In another embodiment (not shown), the notches 300 may beconfigured for ASTM B88 standard pipe sizes as well as EMT pipe sizes.In a further embodiment (not shown), the notches on the stem 295 may beeliminated to accommodate for any pipe size. In such an embodiment, thelocking plate 365 would engage with the stem 295 and hold the stem 295in place via friction. Pivoting movement of the locking plate 365 alsomoves the forward portion 368 of the locking plate 365 into engagementwith a rear surface 370 of the upper carriage body 200 (FIG. 11).Engagement of the locking plate 365 with the upper carriage 175 and thestem 295 locks the carriages 175, 180 relative to each other in a lockedstate. In the locked state, the carriages 175, 180 rotate as one unit,which prevents the inserted pipe from wobbling during rotation of thecutting head assembly 145 and reduces the risk of cutting imperfections.

As shown in FIGS. 5A-5D, the cutting head assembly 145 also includes astop lever 375, coupled to an interior portion of the housing 105. Thestop lever 375 includes a curved first side edge 380 proximate thecutting area 185 and an opposite second side edge 381. Side edge 380allows continued rotation of the cutting head assembly 145 withoutinterference by the lever 375 (FIG. 5C). A lower corner 385 of the stoplever 375, where the curved side 380 terminates, operates to terminaterotation of the cutting head assembly 145, remove the load on the firstand second springs 225, 226, and unlock the upper and lower carriages175, 180. The stop lever 375 is coupled to the housing 105 at a pivotpoint 376. The stop lever 375 is biased to a first position, toward thecutting area 185 (FIG. 5A-5D), by a biasing mechanism, such as a torsionspring (not shown). The travel path of the stop lever 375 is defined bya slot 377 in the stop lever 375 and a pin 378 coupled to an interiorportion of the housing 105 and extending through the slot 377.

As the cutting head assembly 145 continues to rotate through as manyrevolutions as necessary to complete the cut, the cam lever 260 remainsaligned with the outer periphery 350 of the cutting head housing 146such that the cam post 265 does not impede the rotation of the cuttinghead assembly 145. When the cutting head assembly 145 has rotated nearly360 degrees from its original position, the cam post 265 contacts thestop lever 375 (FIG. 5C). Upon contact between the cam post 265 and thestop lever 375, the force of the contact overcomes the force of thelever torsion spring (not shown) to move the stop lever 375 away fromthe cutting area 185 and to a second position, as shown in FIG. 5C. Withthe stop lever 375 in this second position, the cam post 265 continuesto move freely along the side edge 380 of the stop lever 375.

The cutting head assembly 145 continues to rotate until the cuttingoperation is complete. When a cutting operation is complete, the useractivates the direction switch 127 to reverse the cutting head assembly145 to the original “home” position (FIG. 5A) such that the pipe cutter100 is ready to begin another cutting operation. As shown in FIG. 5D,during the rotation of the cutting head assembly 145 in the reversedirection, the cam post 265 engages the lower corner 385 of the stoplever 375. Upon engagement, cam 250 rotates until fully extended andback to the original home position shown in FIG. 5A, thereby releasingthe load on the cutting springs 225, 226 and returning the upper andlower carriages 175, 180 to the unlocked state. Further rotation of thecutting head assembly 145 in the reverse direction, causes the stoplever 375, which is now in the first position, to engage a stop boss 390located on the cutting head housing 146. As the stop lever 375 engagesthe stop boss 390 and provides resistance to further rotation, theclutch 151 slips out of engagement with the bevel gear 153 and therebyterminates further rotation of the drive assembly 140 and the cuttinghead assembly 145. At this point, the cutting head assembly 145 ispositioned in its original home position, with the upper and lowercarriages 175, 180 in the unlocked state to release the cut pipe fromthe cutting area 185 and accept another pipe to be cut.

The time required for cutting a pipe varies based upon at least a pipediameter, a pipe thickness, or a pipe material. In the illustratedembodiment, the motor 130 of the pipe cutter 100 operates at betweenabout 370 revolutions per minute (RPM) and about 390 RPM. The followingchart provides examples of the average cut time (in seconds) andrevolutions per cut for a variety of copper pipes that may be used withthe pipe cutter.

Pipe Type ½″ M ½″ L ½″ K ¾″ M ¾″ L ¾″ K 1″ M 1″ L 1″ K Average 2.54 4.425.55 3.22 6.29 15.19 5.65 11.12 20.74 Cut Time Revolutions 12-16 21-2827-36 15-20 30-40 74-98 27-36 54-72 101-134 Per Cut

Referring to FIG. 12, the pipe cutter 100 includes a fuel gauge 395 toassist a user in evaluating the remaining battery life. The fuel gauge395 is located in an easily viewable region of the pipe cutter 100 onthe housing 105. The fuel gauge 395 may be illuminated by one or moreindicator lights, such as one or more light emitting diodes (LEDs). Asshown in FIG. 12, the illustrated fuel gauge 395 displays four differentindicators relating to four different battery lives. For example, fourlit LEDs indicate a 100% battery life remaining, three lit LEDsindicates 75% battery life remaining, two lit LEDs indicate 50% batterylife remaining, one lit LED indicates 25% battery life, and one flashingor blinking LED indicates a battery life of 10% or less. In someembodiments, a flashing or blinking LED may indicate to the user thatthe battery pack 120 needs to be charged or replaced. The fuel gauge 395is selectively activated by a switch 400, or may remain illuminated atall times during the operation of the pipe cutter 100.

FIG. 13 illustrates another embodiment of a cutting head assembly 445.The cutting head assembly 445 is similar to and operates similarly tothe cutting head assembly 145 shown in FIGS. 1-11; therefore, likestructure will be identified by the same reference numerals. The cuttinghead assembly 445 includes one or more additional mechanisms configuredto interact with the cam lever 260 and cam post 265 during rotation.

As shown in FIG. 13, when the cutting head assembly 445 begins torotate, the cam lever 260 engages the cam actuator 355, as discussedabove, and engages a movable lever 450. The movable lever 450 replacesthe stop lever 375 of the previous embodiment. In the illustratedembodiment, the movable lever 450 is spring-biased away from the upperand lower carriages 175, 180. As the cam lever 260 moves into alignmentwith the cutting head assembly 445 (as discussed above with respect toFIGS. 5A-5B), the cam lever 260 rotates the movable lever 450 toward theupper carriage 175 until the cam lever 260 is able to move past themovable lever 450 and the cam actuator 355. With the cam lever 260aligned with the cutting head assembly 445, the cutting head assembly445 continues to rotate. When the cutting process is completed, a usermoves the direction switch to a reverse mode to return the cutting headassembly 445 to the home position. As the cutting head assembly 145moves in the reverse direction, the cam lever 260 engages a tip 455 ofthe movable lever 450. The engagement forces the movable lever 450 torotate toward the upper carriage 175 and forces the cam lever 260, andconsequently, the cam 250, to rotate out of alignment with the cuttinghead assembly. The rotation removes the load from the first and secondsprings 225, 226 and unlocks the upper and lower carriages 175, 180.

FIGS. 14-21 illustrate a pipe cutter 500 according to another embodimentof the invention. Similar to the previously described embodiments, thepipe cutter 500 receives power from a battery 505. The pipe cutter 500includes a housing assembly 510 including a body 515 and a handleportion 520. The body 515 defines a forward portion 522 that supports acutting head assembly 525. The body 515 of the pipe cutter 500 alsoincludes a motor 530. The operation of the battery powered motor isimplemented in a similar fashion to that of the previous embodiments,including a control circuit 532.

As shown in FIG. 15, pipe cutter 500 includes a drive assembly 535, suchas the drive assembly 140 described with respect to FIG. 2A. The driveassembly 535 includes a drive gear 540, a first idler gear 545, a secondidler gear 550, and a head gear 555. Similar to previously discussedembodiments, the drive assembly 535 operates to rotate a cutting headassembly 525, which in turn, causes a cutting carriage 560 to facilitatethe cutting operation.

A cutting head assembly 525 and portions of the cutting head assembly525 are shown in FIGS. 16-21. In these embodiments, the cutting headassembly 525 is configured to receive and cut pipes of various sizes,thicknesses and materials. For example, in the illustrated embodiment,the cutting head assembly 525 accommodates ½″ diameter pipe (designatedwith reference number 565), ¾″ diameter pipe (designated with referencenumber 570) and 1″ diameter pipe (designated with reference number 575).In other embodiments, the cutting head assembly 525 may be configured toreceive and cut a fewer or greater number of pipe sizes than shown anddescribed and/or different pipe sizes and thicknesses than shown anddescribed.

As shown in FIG. 16, the cutting head assembly 525 includes a cuttinghead 600 having a first area 601 and a second area 603. The cutting head600 defines an opening 602 in which to receive a pipe or workpiece forcutting. The cutting head 600 also defines a cutting area 604 in whichto position the pipe for cutting. As shown in FIG. 16, the cutting area604 is generally circular and has a center point 606. The pipe ispositioned within the cutting area 604, such that a longitudinal axis ofthe pipe is positioned roughly within the center point 606 of thecutting area 604. As shown in FIG. 16, the first area 601 of the cuttinghead 600 is positioned on one side of the center point 606 and thesecond area 603 of the cutting head 600 is positioned on the other sideof the center point 606 across from the first area 601. As discussedbelow, the cutting head 600 rotates around the pipe roughly about thecenter point 606 during the cutting operation.

In the illustrated embodiment, the cutting head assembly 525 alsoincludes a blade or cutting wheel 605 mounted to a cutting wheelcarriage 610. Portions of both the cutting wheel 605 and the cuttingwheel carriage 610 are contained within and supported by the cuttinghead 600. As shown in FIG. 16, the cutting wheel carriage 610 includes acutting wheel mounting portion 612, a supporting leg portion 613 coupledto and extending from the cutting wheel mounting portion 612 and an armportion 614 coupled to and extending from the supporting leg portion613. A portion of the cutting wheel 605 protrudes from the first area601 of the cutting head 600 and the cutting wheel carriage 610 into thecutting area 604.

The cutting head assembly 525 may also include a roller assembly 615. Asshown in FIG. 16, at least a portion of the roller assembly 615 iscontained within and supported by the cutting head 600. The rollerassembly 615 also includes a portion which protrudes into the cuttingarea 604. The cutting area 604 is positioned between the roller assembly615 and the cutting wheel 605 and wheel carriage 610. During operation,the pipe to be cut is centered within the cutting area 604 by the rollerassembly 615, as discussed below.

The roller assembly may include one or more rollers mounted on a rollercarriage 620. In the illustrated embodiment, the roller assembly 615includes a first roller 625 and a second roller 630 mounted on theroller carriage 620.

The roller assembly 615 may also include an adjustment plate 640. Thedistance that the roller assembly 615 protrudes into the cutting area604 may be adjusted via the adjustment plate 640. As shown in FIG. 20,the adjustment plate 640 includes three (3) fittings: a first fitting650, a second fitting 655 and a third fitting 660. The roller carriage620 includes an aperture 665 for receiving a set screw. The set screwcouples the roller carriage 620 to the adjustment plate 640 through oneof the three fittings 650, 655, 660. In the illustrated embodiment, thefittings 650, 655, 660 correspond to the three different sizes of pipethe pipe cutter 500 may cut. For example, the roller assembly 615 may beadjusted to accommodate the ½″ diameter pipe by coupling the rollercarriage 620 to the adjustment plate 640 through the first fitting 650.Also as an example, the roller assembly 615 may be adjusted toaccommodate the ¾″ diameter pipe by coupling the roller carriage 620 tothe adjustment plate 640 through the second fitting 655. The rollerassembly 615 may be further adjusted to accommodate the 1″ diameter pipeby coupling the roller carriage 620 to the adjustment plate 640 throughthe third fitting 660.

As shown in FIGS. 16-21, the cutting head assembly 525 further includesa timing gear 675, a worm screw 680, an advancing gear 685, a threadedcutting screw 690, and a pawl 695. In the illustrated embodiment, thetiming gear 675 is fixed to the housing 510 and does not rotate with thecutting head 600. The timing gear 675 includes a non-threaded portion676 and a threaded portion 677. Only the threaded portion 677 of thetiming gear 675 engages with the worm screw 680, as shown in FIG. 18.

The worm screw 680 is mounted to the cutting head 600 and engages withboth the threaded portion 677 of the timing gear 675 and the advancinggear 685. The advancing gear 685 is coupled to the end of the threadedcutting screw 690. Thus, the threaded cutting screw 690 rotates or spinswith the advancing gear 685. The pawl 695 is threadedly engaged with thethreaded cutting screw 690 and moves up and down the screw 690 dependingon the direction of rotation of the cutting screw 690 and advancing gear685.

The pawl 695 may be further coupled to the cutting head carriage 610 viaa connection pin 696 (FIG. 20). As shown in FIG. 20, the pawl 695 pivotsabout the connection pin 696 from a closed or engaged position (FIG. 16)and an open or disengaged position (FIG. 19). In the closed position,the pawl 695 is threadedly engaged with the threaded cutting screw 690.In the open position, the pawl 695 is no longer threadedly engaged withthe threaded cutting screw 690. As shown in FIG. 19, the pawl includes athreaded portion 697 which engages with the screw 690. When the pawl 695moves with respect to the screw 690 (as will be discussed below), thethreads bias the pawl 695 into the closed position. Also, as shown inFIG. 19, the pawl 695 includes a pawl pin 698 extending outwardly fromthe pawl 695.

As shown in FIGS. 16-21, the cutting head assembly 525 further includesa release 700, a trip lever 705, a trip frame 710 and a spring 720. Thetrip frame 710 is a metal frame supported by the housing 510. The tripframe 710 does not rotate with the cutting head 600 during operation.The trip lever 705 is mounted on the trip frame 710 and is biased towarda catch or stop surface 730 of the trip frame 710 via a trip spring.

As shown in FIGS. 18 and 21, the release 700 includes a pin 740 thatextends through a pin opening 745 defined by the cutting head 600. Therelease 700, and thus the pin 740, is biased toward the cutting area 604of the cutter 500 by a spring. The release 700 includes a slot 750 whichreceives the pawl pin 698 of the pawl 695. As the pawl 695 moves up anddown the threaded cutting screw 690, the pawl pin 698 slides up and downthe slot 750 of the release 700.

The spring 720 is a light spring which applies a smaller force to thecutting wheel carriage 610 when the pawl 695 is disengaged with thethreaded cutting screw 690. When the pawl 695 is disengaged, the cuttingwheel carriage 610 is free to move along the threaded cutting screw 690.However, the force applied by the spring 720 biases the carriage 610,and thus the cutting wheel 605, downward. In the illustrated embodiment,the force of the pipe, when inserted into the cutting area 604,overcomes the force exerted by the spring 720. When the pipe isinserted, the pipe forces the cutting wheel 605 upward, which forces thecutting wheel carriage 610 to move up the threaded cutting screw 690 and“snap” the pawl 695 into engagement with the screw 690.

Operation of the pipe cutter 500 will be described with respect to FIGS.15-21. First, the user selects the pipe to be cut and positions the pipewithin the cutting area 604. As discussed above, when the pipe isinserted into the cutting area 604, the pipe pushes the cutting wheel605 (and thus the cutting wheel carriage 610) upward and snaps the pawl695 into engagement. Based on the diameter of the pipe, the user adjuststhe roller carriage 620 to the appropriate height, such that the piperests on the first and second rollers 625 and 630.

When the user activates the ON position of a trigger from the OFFposition, the motor 530 is energized by a battery 505 to drive the drivegear 540 in a forward direction. The drive gear 540 and the remainder ofthe drive assembly operate in the same or similar manner to the driveassembly discussed in previous embodiments.

Referring to FIGS. 16-17, the cutting head 600 now rotates in forwarddirection and moves the cutting wheel 605 around the circumference ofthe pipe. As the cutting head 600 rotates and the cutting wheel 605 cutsthe pipe, the worm screw 680 engages with the threaded portion 677 ofthe timing gear 675 and rotates clockwise. When the worm screw 680passes the threaded portion 677 of the timing gear 675, the worm screw680 is no longer in engagement with the timing gear 675 and stopsrotation. Accordingly, during one revolution of the cutting head 600,the timing gear 675 only engages with the worm screw 680 for a portionof that revolution and only advances the screw 680 a few revolutions.

The clockwise rotation of the worm screw 680 drives the advancing gear685 in a counter-clockwise manner, but again, only when the worm screw680 is engaged with the threaded portion 677. Every time the advancinggear 685, and in turn the cutting screw 690, is driven in thecounter-clockwise manner, the threaded cutting screw 690 forces the pawl695 to move down the threaded cutting screw 690. This in turn forces thecutting wheel carriage 610 to move downward toward the cutting area 604at a certain rate. In the illustrated embodiment, this assembly isconfigured such that the cutting wheel carriage 610 (and thus thecutting wheel 605) advances 0.004″ per revolution of the cutting head600. In other embodiments, the feed rate of the cutting wheel 605 may begreater than or less than the feed rate shown and described.

Also, as the cutting head 600 rotates clockwise, a ridge 800 coupled tothe outside surface of the cutting head 600 engages with the trip lever705 and overcomes the force of the trip spring to bias the trip lever705 away from the cutting area 604. When the end portion 805 of theridge 800 passes, the trip spring biases the trip level 705 back againstthe catch 730 of the trip frame 710 until the next revolution.

During each revolution of the cutting head 600, the cutting wheel 605advances downward toward the cutting area 604 at the feed rate describedabove. Once the cutting wheel 605 has completed the cut, the userselects the reverse position of the trigger. This reverses the directionof the motor 530 and the cutting head 600 is driven in acounter-clockwise manner as shown in FIG. 16.

Referring to FIG. 16, as the cutting head 600 rotates in acounter-clockwise manner, the pin 740 of the release 700 is forced awayfrom the cutting area 604 by the trip lever 705. The release 700, inturn, forces the pawl 695 to disengage with threaded cutting screw 690and the cutting wheel carriage 610 is biased back down in the homeposition, ready for the next cut.

In the illustrated embodiment, for example, the pipe cutter 500 with afeed rate of 0.004″ per revolution cuts a ¾″ diameter type pipe in eight(8) revolutions. At 620 revolutions per minute, the cut takesapproximately four (4) seconds. In other embodiments, the feed rate andspeed of the cutter 500 may be optimized for certain pipe sizes, typesand/or materials.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe scope and spirit of one or more independent aspects of the inventionas described.

1. A pipe cutter for cutting a pipe, the pipe cutter comprising: acutting head assembly including a first carriage and a second carriagespaced apart to define a cutting area, the first carriage having a firstportion supporting a cutting mechanism and the second carriageconfigured to support a pipe within the cutting area, wherein thecarriages have a locked state and an unlocked state, and further whereinwhen the carriages are in the unlocked state, the carriages are movablerelative to each other and biased into the cutting area; a driveassembly configured to rotate the cutting head assembly; and a lockingmechanism configured for changing the carriages from the unlocked stateto the locked state and for holding a second portion of the firstcarriage in a locked state relative to the second carriage, the lockingmechanism comprising, an actuation member rotatably coupled to thesecond portion of the first carriage, wherein rotation of the cuttinghead assembly causes rotation of the actuation member relative to thefirst carriage, and a locking member configured for engagement with thefirst carriage and the second carriage upon rotation of the actuationmember, wherein engagement of the locking member with the first carriageand the second carriage holds the carriages in the locked state, whereinthe first carriage includes a biasing member between the first portionand the second portion, wherein upon rotation of the cutting headassembly the actuation member rotates relative to the first carriage anddeflects the biasing member such that a biasing force acts on thecutting mechanism to cut the pipe.
 2. The pipe cutter of claim 1 whereinthe cutting mechanism includes a blade.
 3. The pipe cutter of claim 1wherein the second carriage includes a pair of rollers.
 4. The pipecutter of claim 1 wherein the actuation member comprises a cam, the camincluding a cam shaft, a lever extending from the cam shaft, and a postpositioned at a free end of the lever.
 5. The pipe cutter of claim 4,and further comprising a cam actuator fixed relative to the cutting headassembly, wherein the cam actuator engages the post to rotate the cammember as the cutting head assembly rotates.
 6. The pipe cutter of claim1 wherein the locking mechanism further comprises a support membercoupled to the second carriage and the locking member engages thesupport member upon rotation of the actuation member to hold thecarriages in the locked state.
 7. The pipe cutter of claim 6 wherein thelocking member comprises, a lift member selectively engageable with theactuation member for movement relative to the support member as theactuation member rotates; and a locking plate for engaging the supportmember and the first carriage, wherein the lift member moves the lockingplate into engagement with the support member and the first carriage. 8.The pipe cutter of claim 7 wherein the support member includes aplurality of notches, each notch corresponding to a position of thecarriages in the locked state.
 9. The pipe cutter of claim 8 whereinwhen the carriages are in the locked state, the locking plate engagesone of the plurality of notches to hold the carriages in thecorresponding position of the locked state.
 10. The pipe cutter of claim8 wherein each of the positions of the carriages corresponds to a pipediameter.
 11. The pipe cutter of claim 1, wherein in the unlocked statethe carriages are configured to receive the pipe within the cuttingarea.
 12. The pipe cutter of claim 1, wherein in the locked state thecarriages hold the pipe within the cutting area.
 13. The pipe cutter ofclaim 1, and further comprising a battery-powered drive assembly. 14.The pipe cutter of claim 1, and further comprising a housing containingthe cutting head assembly, the housing including a window located in awall of the housing for viewing the cutting area through the housing.15. The pipe cutter of claim 1, and further comprising a water-tightseal located between a forward portion of the pipe cutter including thecutting head assembly and a handle portion of the pipe cutter.
 16. Thepipe cutter of claim 1 wherein the biasing member is a biasing armhaving the first portion and the second portion.
 17. The pipe cutter ofclaim 11 wherein the cutting head assembly further comprises: a springbiasing the second carriage into the cutting area; and an over-centerposition for the pipe, the over-center position defined by the cuttingmechanism and a support surface of the second carriage, wherein in thelocked state the carriages hold the pipe in the over-center position.18. The pipe cutter of claim 1 wherein the cutting head assembly rotatesin a first direction to change the carriages to the locked state and thecutting head assembly rotates in a second direction to release thecarriages to the unlocked state.
 19. The pipe cutter of claim 18, andfurther comprising a release mechanism for releasing the carriages tothe unlocked state, the release mechanism including a lever pivotallycoupled to a housing of the pipe cutter proximate the cutting headassembly, wherein during rotating of the cutting head assembly in thesecond direction the actuation member contacts the lever to release thelocking member from engagement with the first carriage and the secondcarriage.
 20. The pipe cutter of claim 19 wherein the release mechanismincludes a stop boss extending from an outer surface of the cutting headassembly, wherein during rotation of the cutting head assembly in thesecond direction the stop boss contacts the lever to stop rotation ofthe cutting head assembly.
 21. A pipe cutter for cutting a pipe, thepipe cutter comprising: a cutting head assembly including, a firstcarriage including a biasing arm having a first portion with a cuttingmechanism, and having a second portion, a second carriage spaced apartfrom the first carriage to define a cutting area, the second carriageincluding a support surface for supporting a pipe within the cuttingarea, an over-center position for the pipe, the over-center positiondefined by the cutting mechanism and the support surface, wherein thecarriages have an unlocked state for inserting the pipe into the cuttingarea and a locked state for cutting the pipe, wherein when the firstcarriage is in the unlocked state the first carriage is movable relativeto the second carriage and is biased into the cutting area, and a springbiasing the second carriage into the cutting area such that when thesecond carriage is in the unlocked state, the second carriage is movablerelative to the first carriage; a drive assembly configured to rotatethe cutting head assembly; and a locking mechanism configured for movingthe carriages from the unlocked state to the locked state and forholding the carriages in the locked state when the pipe is positioned inthe over-center position, the locking mechanism comprising, an actuationmember rotatably coupled to the second portion of the first carriage,wherein rotation of the cutting head assembly causes rotation of theactuation member relative to the first carriage, and a locking memberconfigured for engagement with the second portion of the first carriageand the second carriage upon rotation of the actuation member, whereinengagement of the locking member locks the second portion of the firstcarriage and the second carriage together and deflects the biasing armsuch that a biasing force acts on the cutting mechanism to cut the pipe.22. The pipe cutter of claim 21 wherein the cutting mechanism includes ablade.
 23. The pipe cutter of claim 21 wherein the support surface ofthe second carriage includes a pair of rollers.
 24. The pipe cutter ofclaim 21, and further comprising a battery-powered drive assembly. 25.The pipe cutter of claim 21, and further comprising a housing containingthe cutting head assembly, the housing including a window located in awall of the housing for viewing the cutting area through the housing.26. The pipe cutter of claim 21, and further comprising a water-tightseal located between a forward portion of the pipe cutter including thecutting head assembly and a handle portion of the pipe cutter.
 27. Thepipe cutter of claim 21, and further comprising: a handle portionincluding a first hand grip and a second hand grip; and a switchassembly positioned on the handle portion between the first hand gripand the second hand grip.
 28. The pipe cutter of claim 21 wherein eachof the carriages includes a forward angled surface proximate an openingto cutting area, the forward angled surfaces being symmetrical andconfigured to guide a pipe into the cutting area.
 29. The pipe cutter ofclaim 28 wherein the biasing arm includes a projection opposite thesupport surface and forward of the over-center position.
 30. The pipecutter of claim 29, wherein each of the carriages includes a rear angledsurface rearward of the over-center position, the rear angled surfacesbeing symmetrical and converging at the rear portion of the cuttingarea.
 31. The pipe cutter of claim 21, wherein the actuation membercomprises a cam member, the cam member including a cam shaft, a leverextending from the cam shaft, and a post positioned at a free end of thelever.
 32. The pipe cutter of claim 31, and further comprising a camactuator fixed relative to the cutting head assembly, wherein the camactuator engages the cam post to rotate the cam member as the cuttinghead assembly rotates.
 33. The pipe cutter of claim 21, wherein thelocking mechanism further comprises a support member coupled to thesecond carriage.
 34. The pipe cutter of claim 33, wherein the lockingmember comprises: a lift member selectively engageable with theactuation member for movement relative to the support member as theactuation member rotates; and a locking plate for engaging the supportmember and the first carriage, wherein the lift member moves the lockingplate into engagement with the support member and the first carriage.35. The pipe cutter of claim 33 wherein the support member includes aplurality of notches, the locking plate engaging one of the plurality ofnotches when the locking mechanism is in the locked state, each notchcorresponding to a position of the carriages in the locked state. 36.The pipe cutter of claim 35 wherein each of the positions of thecarriages corresponds to a pipe diameter.